With rapid growth of wireless communication information quantity, demand for communication quality becomes stricter. The 5th generation mobile networks (5G) of the wireless communication technologies meet the operation requirements of high rate, high capacity and high quality. Since the current available bands in spectrum are highly congested, applications turn toward higher-frequency bands (>6 GHz). In these bands, the bandwidth for a single system is wider (e.g. about 500 MHz to 2 GHz), and data transmission capacity and system efficiency are increased. To ensure transmission quality of wireless communication signals, high gain antennas are used to transmit wireless communication signals in the prior arts.
Please refer to FIG. 1A, a schematic diagram illustrating a communication device which transmits wireless communication signals in a low-frequency band and utilizes a high gain antenna In order to transmit the signals to a wider range, a communication device 13 using a low-frequency band (e.g. 3G band) to transmit the wireless communication signals will utilize an radiating antenna 13b with a greater transmit power. A controller controls a base band processor 11 and a radio frequency (hereinafter, RF) circuit 13a to generate transmission signals which are then emitted into air through the radiating antenna 13b. However, the antenna 13b with greater transmit power usually generates a lot of heat and increases temperature of the communication device 13.
Due to factors of higher path loss, lower penetration and higher noise in the 5G band, higher power is required for the a transmitting device to transmit the wireless communication signals in the 5G band. As mentioned above, a radiating antenna 13b with higher transmit power will generate more heat so as to affect the performance of the communication device. Hence, the communication device 13 in FIG. 1A is not proper for the 5G band. Another conventional communication device takes advantage of multiple radiating antennas with lower transmit power.
Please refer to FIG. 1B, a schematic diagram illustrating a communication device utilizing multiple antennas with low power gains. The communication device 17 includes a plurality of radiating antennas 17b with lower power, a base band processor 15 and an RF circuit 17a. The antennas 17b in this application should be used with a plurality of amplifiers. The power gain of the amplifiers can assist the communication device 17 to enhance the transmission of the wireless communication signals.
Nevertheless, while using the multiple radiating antennas 17b with lower transmit power, the communication device 17 occupies larger space and further space is required for installation. In some conditions for installation the communication device, the installation space is insufficient for the bulky communication device 17.